"Ration-by-Weight of Efficiency and Equity" discusses a new allocation method in ground delay programs for air traffic flow management that provides a compromise in efficiency and equity between what is provided by the ration-by-schedule method and the ration-by-distance method. The new slot rationing method, called ?RBW,? balances efficiency, equity and max deviation. RBW includes ?slot lock,? a practical way to limit the maximum deviation. A concept called the ?efficiency-equity ratio? evaluates slot exchanges.